When they are used as foundation of the manifold or pipe terminal in deep waters, suction caissons are subjected to torsional except for the vertical force, horizontal force and bending moment applied. Torsion would reduce the vertical bearing capacity, horizontal bearing capacity and bending resistance of caisson foundation. The finite element method is used to study the interaction between caisson foundation and soil, and the influence of torsion on the other bearing capacity components, aimed at caisson with length to diameter ratio of 1-2 in normally consolidated clay. The results show that when the torsion applied is less than 20% of the torsional capacity, the torsion has slight effect on the vertical bearing capacity, horizontal bearing capacity or bending moment. When torsion reaches 20%-80% of the torsional capacity, the other three capacity components can be reduced by no more than 20%.